package dao.impl;

import dao.UserDao;
import pojo.User;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class UserDaoImpl implements UserDao {

    List<User> users=new ArrayList<>();
    Connection connection=null;
    PreparedStatement pst=null;
    ResultSet resultSet=null;

    //jdbc进入数据库  查询
    public List<User> findAll() {
        //jdbc操作
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.获取连接(url,user,password)
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "Aa123456");

            //3.写sql语句
            String sql = "select * from sys_user";

            //4.预编译sql
            pst = connection.prepareStatement(sql);

            //5.有参数设置参数

            //6.执行sql语句
            resultSet = pst.executeQuery();

            //7.遍历结果集
            while (resultSet.next()) {
                User user = new User();//创建一个新的user
                user.setId(resultSet.getInt(1));
                user.setName(resultSet.getString(2));
                user.setPass(resultSet.getString(3));
                users.add(user);//把对象添加到集合里面

            }

            //8.关资源
//        resultSet.close();
//        pst.close();
//        con.close();
//        //把集合中的数据存储到作用域中
//        req.setAttribute("users",users);
//        req.getRequestDispatcher("/user.jsp").forward(req,resp);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        finally {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (pst != null) {
                    pst.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch(SQLException e)
                {
                    throw new RuntimeException(e);
                }
        }
        return users;
        }

    }

